No they're trying to make the animation hella good that's why it's in black and white they want to make the final fight as epic as can be.
I hope so.Highly doubt it. They're either behind schedule or has produced such stunning work that they don't want to reveal prior to the premier....or maybe the b&w is a homage to the manga's end and only lasts like one scene at the beginning of the episode to mark the epicness of the moment.
This^^^It's just SP paying a tribute to the manga by using the preview.
It will be the best animated episode of the Naruto series (even beating Kakashi vs Obito, Madara vs Shinobi Alliance, Six-tailed Naruto vs Pain,etc). They can't spoil what the episode actually looks like.
Actually it's not and that's what worries me. What we saw were tracings of manga panels accompanied with the screentones and shading with minimal digital animation. Whatever it was it was purposeful mimmicking of the manga. Rough animation sketches don't look like that.No, it's just to tease.
I think what they've actually shown us is the first stage of animation (before in-between frames added, colouring, cleaning etc etc.)